Testing CRT Monitors

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  • Either one computer with dual monitor output or two computers with single output side by side. The computer(s) are left powered on.
  • One large monitor (c. 19") that we consider to have excellent characteristics.
  • For now, we should wget a web page that contains a few images plus small font text, and have the a browser running displaying that image from the local drive. Later, perhaps we should capture that into an image, and have it displaying with a light, standard tool like xsetroot(1X) rather than a full browser.
  • A string marked at 1" intervals with lines drawn with a thin marker and little labels indicating the inch count, attached by transparent tape on the positions of the more common monitor sizes.
  • A short video extension cable permanently attached to the computer that receives the monitors to be tested.


  • Unambiguously identifying the person who tested the monitor will help salespeople adjust to the differences in perception of different testers. One person's 80% brightness can be another person's 60% brightness. We could just use the FGT ID number; adding a name guards against typos and hard to read digits.
  • The pins on the video extension cable will tend to wear out, so the cable will need replacing periodically. But the computer itself will be better protected against wear.
  • These days, VGA isn't the only video connector in the PC world. We may need additional video testing stations to handle different types of connectors. Later, we can try to figure out how to have multiple video cards, each providing different connectors, in the same computer. We could use cable adaptors in some cases, but connecting and disconnecting adaptors from the base cable would increase wear and, I suspect, adaptors aren't as plentiful in the inbound stream.


  • Take a monitor from the inbound pile.
  • Attach it to the workstation marked "monitor testing".
  • Power on the monitor, and wait a few seconds till the image becomes visible.
  • Run its degauss function.
  • Increase the monitor's brightness to maximum.
  • Compare it against the reference monitor next to it.
  • Is the image overly fuzzy? Is the text legible? Would you buy this monitor?
    • If not, put the monitor in the recycling pile.
    • If it's somewhat fuzzy but text was still comfortably legible, continue.
  • Is the image dimmer than the reference one?
    • If it is terribly dim, put the monitor in the recycling pile.
    • If it is somewhat dimmer yet still fairly visible, estimate its brightness as a percentage of the reference monitor (100% = equally bright as the reference monitor; 0% = does not light up at all).
  • Measure the screen diagonally in inches with the string ruler. Round down to a whole inch. Eg if the monitor is a little bigger than the 16-inch mark on the string, consider the monitor to be a 16" one.
  • Make and attach to the front of the monitor, above the middle of the screen, a label containing, in this order:
    • the screen size
    • the brightness percentage.
    • today's date.
    • your FGT ID number and your full name.
  • Put the monitor in the cleaning (for sale or grant) rack.

LCD MONITOR TEST PROCEDURE -today's more common and popular lcd monitors differ from most older Cathode Ray Tube monitors since Liquid Crystal Display units could have 4:3 aspect ratio OR 16:9 OR 16.10 ratios and offer many more connection modes -But have many more failure modes-other than physically caused since ALL are powered on constantly so highly susceptable to line bumps caused by lightning, accidents,and power restoration-so good proper surge protectors highly recommended

A1)-locate suitable KNOWN GOOD cable-vga or dvi or hdmi-possibly "s" video -and connect to video card of same configuration on PC,or notebook or netbook -not all configurations supported on all units A2)-powering on unit,observe IF scratched,cracked,spotted ,vertical OR horizontal streaking is visible or if unit is DEAD-put aside and record flaws A3)-observe colour purity on initial power "on"-might have reddish tinge for few seconds than SHOULD settle down to pure white-record A4)-video image should fill full screen-whether 4:3 or 16:9 or 16:10-adjust from "menu" on front or side as suitable A5)-look for dead pixles,blotches,fading in background A6)-connect speaker cable if provided-test A7)-adjust brightness,hue etc by menu bottons -[lower settings 50-75 % will ensure longer ccfl Cold Cathode florescent Lamp(s) life] -average max ccfl lamp life is 6-7 years run thus and SHORTER if run 100 % A8)-"reddish" hue on power on may indicate failing ccfls or invertor failure-record


B1)-IF unit boots to screen,then just flashes or dies outright,record then put unit aside B2)-IF cracked or badly streaked,record then put aside B3)-IF speakers included,connect and test-but if no audio or distorted,record and put aside B4)-IF not full screen,even after menu adjust,the video card in PC OR monitor,might be faulty -the PC's video card OR cable might be faulty-replace and retest-record and put aside


C1)-DEAD ,cracked,streaked or dim screen units are HIGHLY suspect -MOST units are NOT cost effective to repair today C2)-However,the ccfl lamp(s)MIGHT be useable-since largely UNAVAILABLE but requires difficult disassembly -an awkward job since most units are heatsealed since not made to be serviced C3)-so remove all metal shields to get to power supply,possibly seperate invertor board,sound card and main video card C4)-then using FINE PRECISION ph 0 bit, remove screens bezle and extract the lcd panel itself,the precision clear light diffuser,freznel panels to get to ccfls -note VERY FRAGILE and minor gasseous MERCURY-DO NOT INHALE if ccfl lamp(s) cracked!!!!! C6)-put ccfl lamp(s) aside in secure place AFTER recording LENGTH and if ends "blackening" -test ccfl lamp(s) on invertor card-that has SAME pinouts/configuration

(many monitors have 4 to 6 ccfl lamps-2 of which MIGHT cost MORE than new monitor)

C7)-many other REPAIRS possible -but NOT COST EFFECTIVE and well beyond freegeek level

C8)-better sets have VESA 4 x 100 mm or 4 x 150 mm or 4 x 200 mm mounting so should be KEPT to repair or mount of other such sets-(where base REMOVED for wall/desk mounting so base LOST C9)-such bases MIGHT ALSO have telescoping provision that MIGHT even ROTATE for standard "portrait" OR "landscape" use on other high end units C10)-SOME even come with usb ports AND/OR AMPLIFIED SPEAKERS -to really minimise desk space